The present invention relates to a device and an apparatus for treating a patent foramen ovate by preventing an over-flap of the patent foramen ovate of a heart septum.
The foramen ovale is present in the interatrial septum. The foramen ovale works as a valve in a fetal heart Under normal conditions, the foramen ovale closes a few months after birth. The case in which the foramen ovate does not close after birth is called the patent foramen ovate. About 20% of adults have the patent foramen ovale. In a normal heart the internal pressure of the left atrium of heart is higher than that of the right atrium of heart, and the septum primum covers the foramen ovale as a valve. Therefore blood does not flow from the left atrium of heart to the right atrium of heart However, when the internal pressure of the right atrium of heart becomes higher than that of the left atrium of heart when a person becomes tense, the septum primum opens toward the left atrium of heart Thereby the blood flows from the right atrium of heart to the left atrium of heart When a thrombus is contained in venous blood flowing from the right atrium of heart to the left atrium of heart, the thrombus flows in the order of left atrium of heart→left ventricle→main artery→brain. Therefore the patent foramen ovale is said to be a cardiogenic factor of cerebral stroke and migraine.
The following treatments for the patent foramen ovate are performed: medicinal therapy (aspirin, warfarin), sealing surgery to be performed by using percutaneous catheter procedure, and open heart surgery to be performed by using extracorporeal circulation.
The medicinal therapy is the first-choice treatment for the patent foramen ovale. But it is difficult to control a dose and stop bleeding during administration. The percutaneous catheter procedure and the open heart surgery are invasive, but radical, thus giving no anxiety for a return. In the present stage, the open heart surgery is more reliable than the percutaneous catheter procedure in terms of the procedure of sealing the patent foramen ovale. But considering risks in performing the extracorporeal circulation and an invasion in incising skin, the percutaneous catheter procedure is more desirable than the open heart surgery if the percutaneous treatment provides an effect similar to that provided by the open heart surgery.
The device, for sealing the patent foramen ovale, which uses the percutaneous catheter procedure is retained at the portion of a congenital septal defect More specifically, to seal a hole in the septum, the procedure of retaining two disk-shaped films at the left atrium of heart and the right atrium of heart is adopted to sandwich the hole.
In the case of the cerebral stroke and the migraine, it is unnecessary to use the film to seal the septum primum which is usually sealed. In this case, it is possible to simplify the construction of the device. Retaining the device to cover the defect at the left atrium of heart and the right atrium of heart causes the thrombus to attach to the left atrium of heart and the like because the device has a large area. Thereby there is a possibility that the thrombus formed at the left atrium of heart causes a patient to have the cerebral stroke and that the device damages the thin septum primum. Thus there is a demand for development of a device of specific use.
To seal a hole of congenital diseases such as atrial septal defect (ASD), ventricular septal defect (VSD), and patent ductus arteriosus (PDA), the material for sealing septal defect is disclosed in EP1222897. The material for sealing septal defect is applicable to the patent foramen ovale. In using the material for sealing septal defect, the member is inserted into the hole by passing the member through the flap which is usually sealed. Thus there is a possibility that the frail septum primum is broken. Further because the member has a large area, there is a possibility that the thrombus attaches to the left atrium of heart or is discharged therein. Thus it is necessary to perform antiplatelet treatment to prevent the generation of the thrombus. As another problem of the method of using the material for sealing septal defect a large catheter is used because the disk-shaped material is accommodated in the catheter by folding it The device developed for carrying out this method is used specifically for a flap-shaped patent foramen ovale. Thus the risk of forming the thrombus is decreased by reducing the size of the member to be retained in a portion to be cured. When this method is used to perform antiplatelet treatment, effects such as reduction of a treatment period of time and a dose can be expected. Further it is possible to reduce the size of the catheter.
The clip-type device for sealing the patent foramen ovale for locking the flap is disclosed in U.S. patent Publication No. 2003/225421. In this device, the member shaped by using the material having a spring action is accommodated in the catheter by folding it. Folding the member to make the catheter small causes an excessive load to be applied to a bent portion. Thereby there is a possibility that the member loses the spring action and gives damage to the flap.
The device for sealing the patent foramen ovate is disclosed in WO2002/098298. The device nay also give damage to the flap.
It is an object of the present invention to provide an apparatus including a device, for treating a patent foramen ovate, which little damages a septum primum (flap) usually sealing the foramen ovale and little applies a load thereto, restrains the flap from opening toward the left atrium of heart, and is capable of preventing blood from flowing from the right atrium of heart to the left atrium of heart in spite of a patent foramen ovale.